U.S. patent application Ser. No. 13/538,456, entitled Interleaved Signaling, and U.S. patent application Ser. No. 13/841,313, entitled Orthogonal Signal Demodulation, the disclosures of which are hereby incorporated by reference in their entireties, relate to the transmission, modulation and demodulation of data through the use of various signaling techniques. The signaling described in the incorporated patent applications, as well as other types of wired and wireless signaling, may be susceptible to impairments added to the transmitted signal as it traverses a signal path. Particularly problematic impairments may result from random noise and/or burst noise. Random noise may be continuous in the time domain and generally flat or “white” in the frequency domain. Burst noise may be strong in amplitude, but relatively short in duration, which may include the noise being wide in frequency. Burst noise may be caused by switching in electrical circuits, such as switching regulated power supplies, switching inductive loads with mechanical contacts, automotive ignitions, and power supplies in compact florescent lamps, etc. Forward error correction (FEC), Reed-Solomon (RS) codes, low-density parity codes (LDPC) and other techniques, such as but not necessarily limited to those described in the incorporated patent applications, may be used to ameliorate channel errors resulting noise related impairments. The use of such codes requires access to the transmitted data and/or an ability to process transmitted signaling at a data level. Additionally, when faced with a strong noise, such as but not necessarily limited to a noise burst, such correction techniques may be may overpowered, resulting in uncorrected signaling and a need for retransmission, if possible.
One non-limiting aspect of the present invention contemplates a need to characterize or estimate the noise related impairments in order to facilitate additional corrective or compensatory measures, optionally in addition to the measures commonly available in the art and/or without having to identify data or process data included within the transmitted signaling. The ability to characterize and/or estimate noise or other signaling impairments without having to identify or process transmitted data can be beneficial, particularly when the noise impairments overlap transmitted signaling in both the time and frequency domains.